Colocated entity type configurations with entities

Added tenant entities and models
Modified db context

PostFundManagement.Domain/Models/TenantUser.cs

@@ -0,0 +1,16 @@
+namespace PostFundManagement.Domain.Models;
+
+public class TenantUser
+{
+    public long Id { get; set; }
+
+    public DateTime CreatedAt { get; set; }
+
+    public Guid CreatedBy { get; set; }
+
+    public long TenantId { get; set; }
+
+    public Guid UserId { get; set; }
+
+    public ActivityStatus Status { get; set; }
+}